The overall purpose of this investigation is to study the physiology of eye movement within the framework of the central neuronal organization of the vertebrate oculomotor system and to provide a detailed analysis of the vestibulo-ocular projection to certain ocular nuclei. The experiments will be designed to reveal the pathways, localization and type of vestibular information arriving at the level of the ocular nuclei during defined eye movements. The specific aims of these experiments are to ascertain the neuronal operations of the oculomotor systems especially that of the motoneurons during eye movement. The techniques to be utilized will be the standard electrophysiological ones comprising intracellular and extracellular recordings from motoneurons and vestibular neurons in anesthetized and unanesthetized preparations. Particular aspects of motoneuronal morphology comprising light and electron microscopy will be correlated with the electrophysiology data. These studies should provide fundamental information not only about ocular motoneurons but also neurocommunication in terms of basic synaptic mechanisms operative during labyrinthine control of eye movement.